Method of separating oil

ABSTRACT

A method of separating oil from a composition containing an oil and water emulsion, by adding a separation additive which is a fatty ester of alkoxylated glycerol, and performing at least one oil separation step. The method is particularly suitable for separating corn oil from stillage produced in a corn ethanol mill.

This application is the U.S. national phase filing under 35 U.S.C. §371of International Application No. PCT/US2016/012583, filed on 8 Jan.2016, and claims the benefit of priority of, U.S. ProvisionalApplication No. 62/104,174, entitled METHOD OF SEPARATING OIL, filed on16 Jan. 2015, the contents of which are incorporated herein by referencein their entirety for all purposes.

FIELD OF INVENTION

The present invention relates to a method of separating oil from anemulsion containing composition, preferably a biomass, particularlystillage, using a separation additive which is an alkoxylated ester.

BACKGROUND

There is growing interest in the use of bioethanol to supplement fossilfuels as an energy source in transport. For example, ethanol accountedfor 9% of gasoline consumption in the USA in 2009, and 90% of theethanol produced in the USA in 2009 was produced using corn asfeedstock. The majority of existing corn ethanol mills, and almostexclusively all the corn ethanol mills commissioned in recent years, areso called “dry mills”.

A “dry mill” plant processes corn into ethanol through a dry grindingprocess. The ground corn is mixed with water to form mash, and then anenzyme is added to convert corn starch into sugar. A fermentationprocess is followed to convert the sugar into ethanol. The liquidintermediate, called “beer,” is further processed by distillation andethanol is collected. The leftover in the “beer” after the removal ofethanol is called stillage, which contains water, protein, nutrients,fibre, and corn oil. The stillage includes an aqueous phase and an oilphase. The corn oil may be separated from the stillage by using acentrifuge and collected as a higher value co-product. A separationadditive may be added into the stillage to enhance the separation of theoil phase from the water phase and increase the corn oil yield. Ethanolplants may treat whole stillage from the “beer” column viacentrifugation to produce wet cake and thin stillage, and further treatthe thin stillage stream by subjecting it to multiple effect evaporationto increase the solids content and recover the distillate for return usein the process. As the solids content increases, the thin stillage istypically referred to as syrup. The syrup is typically combined with wetcake or distillers' dry grains (DDG) and sold as animal feed.

The corn oil yield from a stillage depends on many factors, such as cornkernel quality, water content, the particle size of the solids in thestillage, the process temperature of the stillage in the centrifuge, andthe design of the separation equipment. The use of a corn oil separationadditive is intended to increase the corn oil yield.

WO2012/128858 of Hercules Incorporated discloses the use ofpolyoxyethylene(20) sorbitan mono-laurate (polysorbate 20),polyoxyethylene(20)sorbitan mono-stearate (polysorbate 60) andpolyoxyethylene(20)sorbitan mono-oleate (polysorbate 80) as corn oilseparation additives. The specific additives disclosed in WO2012/128858are all based on sorbitan and although the yield of corn oil obtainedfrom stillage in the presence of such additives is improved, there canstill be a significant amount of corn oil left un-collected, anddischarged unseparated from the stillage as part of a product with lowercommercial value. The composition of the stillage can vary considerablyas can the effectiveness of the sorbitan derivatives as oil separationaids with different stillages. There is a need for alternative orimproved separation additives which are also effective with a wide rangeof stillages.

The present invention seeks to aid the recovery of oil from a wide rangeof aqueous compositions, particularly from different biomass materials,and especially from different stillages.

SUMMARY OF THE INVENTION

We have surprisingly discovered a method of separating or recovering oilwhich overcomes or significantly reduces at least one of theaforementioned problems. Accordingly, the present invention provides amethod of separating oil from a composition comprising an oil and wateremulsion, which comprises adding a separation additive to thecomposition and performing at least one oil separation step, wherein theseparation additive comprises a fatty ester of alkoxylated glycerol. Theinvention also provides a stillage and product derived therefromcomprising a fatty ester of alkoxylated glycerol.

The invention further provides a separation additive comprising a fattyester of alkoxylated glycerol obtainable by alkoxylating a mixture of atriglyceride and glycerol.

The invention yet further provides the use of a separation additivecomprising a fatty ester of alkoxylated glycerol to separate oil fromstillage.

All of the features described herein may be combined with any of theabove aspects of the invention, in any combination.

The oil containing composition is suitably a biomass, by which isgenerally meant organic matter harvested or collected from a biologicalsource. The biological source is preferably renewable and includes plantmaterials (e.g. plant biomass), animal materials, microbial materialssuch as bacteria, fungi and algae, and/or materials producedbiologically. The biomass will normally contain glycerides (e.g. tri-,di-, and/or mono-glyceride).

In one preferred embodiment, the composition or biomass is stillage, bywhich is meant a co-product or by-product produced during production ofa biofuel, particularly when using corn as feedstock. The term“stillage” can refer to whole stillage, thin stillage, or concentratedstillage such as condensed distillers soluble, i.e. syrup, which can beproduced from biofuel process streams, e.g. bioethanol productionprocess streams.

The fatty component of the fatty ester of alkoxylated glycerol isgenerally derived from fatty acids or derivatives thereof. Preferably,the fatty ester is derived from fatty acids and/or derivatives thereof.The fatty acids are preferably mono-carboxylic acids and may be linearand/or branched, saturated and/or unsaturated. Unsaturated fatty acidsare preferred. The unsaturated fatty acids may be mono-unsaturated,di-unsaturated and/or poly-unsaturated. Linear fatty acids arepreferred.

The fatty acids suitably have at least 6 carbon atoms, preferably atleast 10 carbon atoms, more preferably at least 12 carbon atoms,particularly at least 14 carbon atoms, and especially at least 16 carbonatoms. The fatty acids preferably have at most 24 carbon atoms, morepreferably at most 22 carbon atoms, and particularly at most 20 carbonatoms. Preferably the fatty acids have in the range from 6 to 24, morepreferably 14 to 22, and particularly 16 to 20 carbon atoms.

Suitable saturated fatty acids may be selected from the group consistingof hexanoic (caproic), octanoic (caprylic), nonanoic, decanoic (capric),undecanoic, dodecanoic (lauric), tridecanoic, tetradecanoic (myristic),2-ethyl hexanoic, trimethylhexanoic, trimethylnonanoic, hexadecanoic(palmitic), octadecanoic (stearic), isostearic, decadecanoic, acids andmixtures thereof. Suitable unsaturated fatty acids may be selected fromthe group consisting of oleic, ricinoleic, linoleic, linolenic, acidsand mixtures thereof. The unsaturated fatty acids may be selected fromthe group consisting of oleic acid, linoleic acid and mixtures thereof.Oleic acid is a preferred unsaturated fatty acid.

The fatty acids are preferably mixtures obtained from natural sources,such as, for example, plant or animal esters, particularlytriglycerides. Fatty acids derived from plant sources are preferred.Suitable natural sources include those selected from the groupconsisting of canola oil, soya bean oil, corn oil, tall oil, palm kerneloil, coconut oil, rapeseed oil, high erucic rapeseed oil, tallow oil andmixtures thereof. Soya bean fatty acids are particularly preferred.Preferably, the fatty acids are selected from the group consisting ofcanola, soya bean, corn, tall, palm kernel, coconut, rapeseed, higherucic rapeseed, tallow fatty acids and mixtures thereof.

In one preferred embodiment, the fatty component of the fatty ester ofalkoxylated glycerol is derived from fatty acids, particularlycomprising, consisting essentially of, or consisting of, soya bean fattyacids.

The fatty ester of alkoxylated glycerol is preferably a partial ester,i.e. preferably not fully esterified.

The fatty ester of alkoxylated glycerol preferably comprises on averageless than 3 ester bonds or fatty chains (e.g. fatty acid residues). Thefatty ester of alkoxylated glycerol suitably comprises on average in therange from 1.0 to 2.5, preferably 1.0 to 2.0, more preferably 1.0 to1.5, particularly 1.0 to 1.2, and especially 1.0 to 1.1 ester bonds (orfatty chains).

The alkylene oxide groups of the fatty ester of alkoxylated glycerol aretypically present as polyalkylene oxide chains of the formula:—(C_(r)H_(2r)O)_(n)— where n is the number of alkylene oxide groups inthe chain, r is 2, 3 or 4, preferably 2 or 3, i.e. an ethyleneoxy(—C₂H₄O—) or propyleneoxy (—C₃H₆O—) group. Preferably the fatty ester ofalkoxylated glycerol comprises a polyalkylene oxide chain. There may bedifferent alkylene oxide groups along the polyalkylene oxide chains.Preferably, it is desirable that the chain is a homopolymeric ethyleneoxide chain. However, the chain may be a homopolymeric chain ofpropylene oxide residues or a block or random copolymer chain containingboth ethylene oxide and propylene oxide residues. Where co-polymericchains of ethylene and propylene oxide units are used, the molarproportion of ethylene oxide units used is suitably at least 50 mol %,preferably at least 70 mol %, more preferably at least 80 mol %, andparticularly at least 90 mol %. The average number of alkylene oxidegroups in the polyalkylene oxide chains of the fatty ester ofalkoxylated glycerol, i.e. the value of the each parameter n, issuitably in the range from 1 to 20, preferably 3 to 10, more preferably4 to 7, particularly 4.5 to 6.5, and especially 5 to 6. The value of theindex n is an average value, which includes statistical variation in thechain length.

The total number of alkylene oxide, preferably ethylene oxide, groups inthe polyalkylene oxide chains of the fatty ester of alkoxylated glycerol(i.e. the average number of alkylene oxide groups in each chains(parameter n)×the number of chains) is suitably in the range from 6 to40, preferably 12 to 30, more preferably 14 to 20, particularly 15 to19, and especially 16 to 18.

The fatty ester of alkoxylated glycerol used herein may be produced in aconventional manner, for example by firstly alkoxylating glycerol, bytechniques well known in the art, for example by reacting with therequired amounts of alkylene oxide, for example ethylene oxide and/orpropylene oxide. The second stage of the process may comprise reactingthe alkoxylated glycerol residue with a fatty acid or a derivativethereof. The direct reaction between the fatty acid and the alkoxylatedglycerol can be carried out, with or without catalysts, by heatingpreferably to a temperature of greater than 100° C., more preferably inthe range from 200 to 250° C. Synthesis using reactive derivatives willusually be possible under milder conditions, for example using lowerfatty acid esters, fatty acid chlorides and/or their respectiveanhydrides. Purification of the reaction product is not usuallynecessary, but can be carried out if desired.

Generally the alkoxylation reaction will replace all of the activehydrogen atoms in the glycerol molecule. However, reaction at aparticular site may be restricted or prevented by steric hindrance orsuitable protection. The terminating hydroxyl groups of the polyalkyleneoxide chains in the resulting compounds are then available for reactionwith acyl compounds to form ester linkages.

In one preferred embodiment, the fatty ester of alkoxylated glycerol isproduced in a transesterification/alkoxylation process, more preferablywhen using a triglyceride and glycerol as starting material. Preferably,the separation additive is obtainable by alkoxylating a mixture of atriglyceride and glycerol. The triglyceride (e.g. soya bean oil) andglycerol can be charged into a reactor vessel together with a basecatalyst (such as NaOH or KOH, normally in aqueous solution at 40 to 50%active levels). With agitation on, the reaction vessel is preferablyheated to about 100° C. and a vacuum applied to remove water. Afterpurging with nitrogen, the reaction vessel is preferably heated to about140° C., and alkylene oxide, for example ethylene oxide and/or propyleneoxide, gradually introduced into the reaction vessel. The addition ofalkylene, preferably ethylene, oxide may take from about 3 to 6 hours,and up to 20 hours to complete at 140 to 155° C. An additional 3 to 6hours may be required to complete the reaction.

The method of producing the fatty ester of alkoxylated glyceroldescribed herein can surprisingly result in a high purity product suchthat the separation additive used herein suitably comprises greater than75 wt %, preferably in the range from 85 to 100 wt %, more preferably 90to 99.9 wt %, particularly 95 to 99.5 wt %, and especially 97 to 99 wt %of fatty ester of alkoxylated glycerol, based on the total weight of theseparation additive.

The separation additive may also comprise an amount of alkoxylated,preferably ethoxylated, fatty ester which may be formed during thesynthesis of fatty ester of alkoxylated glycerol. The alkoxylated fattyester may be a mono-ester, di-ester or a mixture thereof.

The separation additive composition preferably comprises in the rangefrom 0 to 10 wt %, more preferably 0 to 5 wt %, particularly 0.05 to 2wt %, and particularly 0.1 to 1 wt % of alkoxylated fatty ester, basedon the total weight of the separation additive.

The separation additive may also comprise an amount of alkoxylated,preferably ethoxylated, glycerol. The separation additive compositionpreferably comprises in the range from 0 to 8 wt %, more preferably 0 to4 wt %, particularly 0.05 to 2 wt %, and particularly 0.1 to 1 wt % ofalkoxylated glycerol, based on the total weight of the separationadditive.

The separation additive composition may also comprise an amount ofpolyalkylene, preferably polyethylene, oxide. The separation additivepreferably comprises in the range from 0 to 8 wt %, more preferably 0 to4 wt %, particularly 0 to 2 wt %, and particularly 0 to 0.5 wt % ofpolyalkylene oxide, based on the total weight of the separationadditive.

The separation additive preferably has a hydroxyl value (measured asdescribed herein) in the range from 60 to 110, more preferably 70 to100, particularly 80 to 90, and especially 83 to 87 mgKOH/g, an acidvalue (measured as described herein) preferably less than 3, morepreferably less than 1, particularly less than 0.5, and especially lessthan 0.1 mgKOH/g, and/or a saponification value (measured as describedherein) in the range from 30 to 100, more preferably 40 to 75,particularly 45 to 60, and especially 50 to 55 mgKOH/g.

The separation additive suitably has a HLB value (calculated usingGriffin's method as is well known in the art) in the range from 11 to16, preferably 12 to 15, more preferably 13 to 14, particularly 13.2 to13.6, and especially 13.3 to 13.5. The separation additive is preferablyliquid at 25° C., more preferably also liquid at 20° C., particularlyalso liquid at 15° C., and especially also liquid at 10° C. Preferablythe separation additive is acceptable for animal consumption. This maybe required because the composition treated with the separation additiveand/or the separated components thereof may be used for animalconsumption. For example, treated stillage may be used in the productionof distillers' dried grains (DDG) or distillers' dried grains withsolubles (DDGS). DDG or DDGS may be used as an animal feedstock.Preferably the separation additive is acceptable for animal consumption.The separation additive may be generally recognized as safe (GRAS). Therequirement that the separation additive is acceptable for animalconsumption may also influence the concentration of additive which maybe added to the composition, preferably stillage. This is because therewill typically be an upper concentration limit specified for thepresence of the separation additive in the animal feedstock so that itis acceptable for animal consumption. This upper concentration limit maydetermine the maximum concentration of separation additive which may beadded to the stillage. For GRAS, the maximum concentration of separationadditive which may be added to the composition may be 1,000 ppm byweight. If the maximum concentration of separation additive in thecomposition is determined by the presence of the additive in the animalfeedstock then an additive with a higher separation performance will bepreferred to increase the oil yield.

The separation additive may be added to the composition, preferablystillage at a dosage of at most 4,000 parts per million (ppm) ofseparation additive based on the weight of the composition. Theseparation additive may be added at a dosage of at most 3,000 ppm,preferably at most 2,000 ppm, more preferably at most 1,500 ppm,particularly at most 1,000 ppm, and especially at most 800 ppm. Theseparation additive may be added at a dosage of at least 50 ppm,preferably at least 100 ppm, more preferably at least 200 ppm, andparticularly at least 300 ppm.

The separation additive may be added at a dosage of at most 1,000 ppm tosatisfy the requirements to be GRAS. Preferably the separation additiveis added at a dosage rate of at least 50 ppm and at most 1,000 ppm basedon the weight of the composition, preferably stillage.

In general, the process steps in ethanol production which include thedistillation which separates ethanol from the whole stillage and thefurther downstream process steps are known as ‘back-end’ process steps.A typical process flow for the back-end process steps may include:

-   -   1. Distillation to separate ethanol from the whole stillage;    -   2. Centrifugation of the whole stillage to produce thin stillage        and wet cake;    -   3. Evaporation of the thin stillage to produce steam and syrup        (dewatered thin stillage); and    -   4. Drying of the syrup to produce DDGS.

The ethanol production process may be a Delta T or ICM corn to ethanolproduction process.

The method of the present invention may be used with whole stillage,thin stillage or syrup. Preferably the separation additive is added to awhole stillage or a thin stillage. The stillage typically comprisesfibre, protein, lipids and yeast. The oil phase of the stillage mayinclude triglycerides.

The separation operation in the method of the invention may comprise oneor more of a centrifugation operation, evaporation operation and dryingoperation.

Preferably, the separation operation includes centrifugation, and theseparation additive is added to the stillage before or duringcentrifugation. Preferably, the separation additive is added to thestillage before the centrifugation occurs. The separation additive maybe added after the majority of ethanol has been distilled away andbefore centrifugation.

Centrifugation may occur for at least one minute, preferably at leasttwo minutes, more preferably at least 3 minutes. Centrifugation mayoccur for up to 15 minutes, preferably up to 10 minutes, more preferablyup to 6 minutes.

The time between the separation additive being added to the stillage andthe oil phase being separated from the stillage may be at least thirtyseconds, preferably at least one minute, more preferably at least twominutes, and particularly at least 3 minutes. The time between theseparation additive being added to the stillage and the oil phase beingseparated from the stillage may be up to 24 hours, preferably up to 12hours, more preferably up to 4 hours, and particularly up to 1 hour. Thetime between the separation additive being added to the stillage and theoil phase being separated from the stillage may be up to 45 minutes,preferably up to 30 minutes, more preferably up to 15 minutes, andparticularly up to 10 minutes.

The method according to the present invention may be performed aboveroom temperature. The method may be performed at a temperature of atleast 30° C., preferably at least 50° C., more preferably at least 70°C. The method may be performed at a temperature of at most 95° C.,preferably at most 90° C. If the method is performed at a highertemperature, the oil phase and water phase of the composition mayseparate more quickly. The separation additive may advantageously lowerthe temperature required to achieve a predetermined amount of separationby increasing the amount of the oil phase which is separated in apredetermined time without requiring a higher temperature. This mayreduce the amount of heat energy (and therefore cost) required for theseparation operation.

The method of the present invention may increase the amount of the oilphase separated from the composition, preferably stillage, when comparedwith a separation method in which no separation additive is used. Theseparation of an increased amount of the oil phase from the stillage mayimprove the corn oil yield of the process. The separation of anincreased amount of the oil phase from the stillage may also reduce theamount of oily deposits on stillage process equipment downstream of theseparation. This may reduce the need for cleaning of the equipment andso may reduce the amount of downtime required to maintain the equipment.

In addition, the oil, preferably corn oil, recovered using the method ofthe present invention may be of improved quality. The oil recovered mayhave a lower solids content or a lower water content than oil recoveredwithout using the separation additive of the present invention.

As shown in the examples below, the separation additive may performbetter than an equivalent amount by weight of polysorbate 80. Betterperformance in this context should be understood to mean that more ofthe oil phase is separated by the separation additive from an equivalentamount of stillage under an equivalent separation operation than isseparated by an equivalent amount by weight of polysorbate 80.

A predetermined amount of the separation additive may enable at least10% more of the oil phase to be separated from a composition, preferablystillage, than an equivalent amount by weight of polysorbate 80 underequivalent separation conditions. Preferably the separation additive mayenable at least 15% more of the oil phase to be separated from thecomposition, preferably stillage, than an equivalent amount by weight ofpolysorbate 80, more preferably at least 20% more, and particularly atleast 30% more. The separation additive may enable at most 100% more ofthe oil phase to be separated than an equivalent amount by weight ofpolysorbate 80, preferably at most 90% more, more preferably at most 70%more. The increase in oil phase separation may be measured by volume.

The predetermined amount may be at most 1,000 ppm, preferably is 400ppm, of separation additive based on the weight of the composition,preferably stillage.

All of the features described herein may be combined with any of theabove aspects of the invention, in any combination. In addition, anyupper or lower quantity or range limit used herein may be independentlycombined.

In this specification the following test methods were used:

i) Corn Oil Separation

Thin stillage samples obtained from corn ethanol plants were stored in arefrigerator to keep from being spoiled. Prior to the test, a stillagesample was taken out of the refrigerator and heated to 82° C. in anoven. 40 ml of the pre-heated stillage sample was added to a 50 mlcentrifuge tube, and 400 ppm of separation additive was added into thesample. The sample was centrifuged at 7,000 rpm for 3 minutes. Theheight of the clear oil layer was measured (in mm) with a ruler.

ii) Acid Value

The acid value of the separation additive was determined by using ASTMD1980-87 (Standard test method for acid value of fatty acids andpolymerised fatty acids).

iii) Hydroxyl Value

The hydroxyl value of the separation additive was measured by using ASTMD1957-86 (Standard test method for hydroxyl value of fatty oils andacids).

iv) Saponification Value

The saponification value of the separation additive was measured byusing ASTM D5558 (Standard test method for vegetable and animal fats).

v) Chemical Composition

The chemical composition of the separation additive was determined byMaldi-MS. Three solutions were prepared. One contained the separationadditive sample in chloroform at a volume concentration of 1%. Thesecond contained dithranol, a common matrix used for MALDI massspectrometry, dissolved in chloroform at a volume concentration of 1%.The third contained potassium bromide dissolved in methanol at a volumeconcentration of 1%. Portions of the three solutions were combined involume ratios of 100 parts matrix solution, 20 parts sample solution,and 1 part potassium bromide solution. A one-microliter sample of thismixture was spotted onto a MALDI plate, upon which it dried immediately.The MALDI spectrum was acquired using a Bruker autoflex speed MALDI massspectrometer, operated in reflector mode. Immediately prior tocollection of the spectrum of the sample, the mass scale of theinstrument was calibrated using a mixture of peptides provided by Brukerfor this purpose. The spectrum was imported into the data analysisprogram Polymerix™ (Ver. 3.0.0) from Sierra Analytics, Inc. Peaks wereassigned based on knowledge of the reaction chemistry and best fits tothe data.

The invention is illustrated by the following non-limiting examples.

EXAMPLE 1

The fatty ester of alkoxylated glycerol was produced in a one potprocess using the materials listed in Table 1.

TABLE 1 Raw Material Wt (g) Molar Ratio Wt. % Glycerol 90.2 1.86 6.4Soybean Oil (ex Cargill) 462.8 1.0 33.1 Ethylene Oxide 847.0 36.5 60.5Sub-Total 1400 100.0 KOH (45%) 2.0 ~0.07 H₃PO₄ 2.0Reaction Process:i) The soya bean oil and catalyst (caustic potash, 45%) were added to aclean and dry 2-L pressurized Parr reactor at ambient temperature.ii) The reactor was heated slowly to 100° C. with agitation and nitrogensweep on.iii) As the temperature was increased, vacuum was applied to removewater.iv) Once the residual water was reduced to below 0.2% at temperaturerange of 90 to 100° C., the glycerol was added.v) With agitation on, the reaction mixture was purged with nitrogen andthe reactor temperature increased to 130° C.vi) The ethylene oxide was fed into the reactor at the temperature rangeof 130 to 150° C. The ethylene oxide feeding rate was controlled so thatthe reactor pressure did not exceed 50 psig.vii) Once all the ethylene oxide had been added, the reactor pressurewas allowed to decrease at the reaction temperature range of 140 to 150°C. After the pressure drop reached a steady low rate, the reaction wascontinued for another 2 hours.viii) Vacuum was gradually applied to 20 torr or less in order to removeany unreacted ethylene oxide. The reactor temperature and vacuum wereheld for another 1 to 2 hours.iix) The reactor temperature was allowed to cool to 60 to 65° C., theproduct was neutralized with phosphoric acid, and the reaction productwas then discharged. The reaction product had an acid value of 0.07 mgKOH/g, a hydroxyl value of 85.2 mg KOH/g and a saponification value of52.9 mg KOH/g.

EXAMPLE 2

The product produced in Example 1 was used as a separation additive inthe corn oil separation test described herein using a stillage samplefrom a corn ethanol plant. The stillage was treated and the height ofthe clear oil layer (indicating the separation performance) was measuredin millimeters (mm) for 5 samples. The average height was calculated.The results are shown in Table 2.

TABLE 2 Sample No 1 2 3 4 5 Average (mm) Stillage 3 3 3 3 3 3

EXAMPLE 3

This is a Comparative Example not according to the invention. Theprocedure of Example 2 was repeated except that polysorbate 80 was usedas the separation additive instead of the product produced in Example 1.The results are shown in Table 3.

TABLE 3 Sample No 1 2 3 4 5 Average (mm) Stillage 2 2 2 2 2 2

The above examples illustrate the improved properties of the separationadditive, and use thereof, according to the present invention.

It is to be understood that the invention is not to be limited to thedetails of the above embodiments, which are described by way of exampleonly. Many variations are possible.

The invention claimed is:
 1. A method of separating oil from acomposition comprising an oil and water emulsion, which comprises addinga separation additive to the composition and performing at least one oilseparation step, wherein the separation additive comprises a fatty esterof alkoxylated glycerol.
 2. The method according to claim 1 wherein thefatty ester is derived from fatty acids and/or derivatives thereof. 3.The method according to claim 2 wherein the fatty acids are selectedfrom the group consisting of canola, soya bean, corn, tall, palm kernel,coconut, rapeseed, high erucic rapeseed, tallow fatty acids and mixturesthereof.
 4. The method according to claim 1 wherein the fatty ester ofalkoxylated glycerol comprises 1.0 to 2.0 ester bonds.
 5. The methodaccording to claim 1 wherein the fatty ester of alkoxylated glycerolcomprises a polyalkylene oxide chain and wherein the average number ofalkylene oxide groups in each polyalkylene oxide chain of the fattyester of alkoxylated glycerol is 4 to
 7. 6. The method according toclaim 5 wherein the total number of alkylene oxide groups in thepolyalkylene oxide chains of the fatty ester of alkoxylated glycerol is12 to
 30. 7. The method according to claim 1 wherein the separationadditive is obtainable by alkoxylating a mixture of a triglyceride andglycerol.
 8. The method according to claim 1 wherein the separationadditive comprises greater than 75 wt % of fatty ester of alkoxylatedglycerol.
 9. The method according to claim 8 wherein the separationadditive comprises 90 to 99.9 wt % of fatty ester of alkoxylatedglycerol.
 10. The method according claim 1 wherein the separationadditive has a HLB value of 13 to
 14. 11. A stillage and product derivedtherefrom comprising a fatty ester of alkoxylated glycerol.
 12. Thestillage according to claim 11 wherein the fatty ester is derived fromfatty acids and/or derivatives thereof.
 13. The method according toclaim 1 wherein the composition comprising an oil and water emulsion isstillage.